ASTM A193 Grade B7 Chemical Composition

Chrome Moly Alloy Steel

ASTM A193 Grade B7 Chemical Composition

Find typical requirement for ASTM A193 Grade B7 Chemical Composition with allowable variation. Chemical analysis of finished products manufactured to ASTM A193 Grade B7 specification must comply with below requirement. This typical composition is in line with the AISI 4140 / AISI 4142 alloy steel used as a raw material to produce B7 bolts, studs and other external threaded fasteners.

Chemical Composition for ASTM A193 Grade B7

Elements Range Product Variation, Over or Under B
Carbon 0.37-0.49 % D 0.02 %
Manganese, max 0.65-1.10 % 0.04 %
Phosphorus, max 0.035 % 0.005 % over
Sulfur, max 0.040 % 0.005 % over
Silicon 0.15 - 0.35 % 0.02 %
Chromium 0.75-1.20 % 0.05 %
Molybdenum 0.15-0.25 % 0.02 %

B Product analysis - Individual determinations sometimes vary from the specified limits on ranges as shown in the tables. The several determinations of any individual element in a heat may not vary both above and below the specified range.

D For bar sizes over 31/2 in. [90 mm], inclusive, the carbon content may be 0.50 %, max. For the B7M grade, a minimum carbon content of 0.28 % is permitted, provided that the required tensile properties are met in the section sizes involved; the use of AISI 4130 or 4130H is allowed.